Rotating furnace inerting

Abstract

A gas inerting system and method is provided. This system includes a rotary melting furnace with a furnace barrel, a burner, and a charge of metal to be melted; and an injection manifold with a plurality of injection orifices. The burner is configured to produce a flame directed into the furnace barrel, and the plurality of injection orifices are configured to disperse inert gas streams into the furnace barrel, into an inerting region between the burner flame and the charge of aluminum. The metal to be melted may be aluminum. The method of inerting includes rotating the rotary furnace and introducing heat into the furnace barrel by generating the flame, thereby beginning a melt cycle, then introducing the inert gas streams into an inlet to the injection manifold, thereby directing the inert gas streams through the injection orifices and into the inerting region, after a predetermined condition has been met.

What is claimed is: 
     
         1 . A gas inerting system, comprising:
 a rotary melting furnace comprising a furnace barrel, a burner, and a charge of metal to be melted; and   an inert gas injection manifold with a plurality of injection orifices;   
       wherein the burner is configured to produce a flame directed into the furnace barrel,
 wherein the plurality of injection orifices are configured to disperse inert gas streams into the furnace barrel, into an inerting region between the burner flame and the charge of aluminum. 
 
     
     
         2 . The system of  claim 1 , wherein the metal to be melted is aluminum. 
     
     
         3 . The gas inerting system of  claim 1 , wherein the injection manifold has a semicircular shape, wherein the plurality of injection orifices is generally equidistant from the burner. 
     
     
         4 . A method of inerting, utilizing the system of  claim 1 , the method comprising:
 rotating the rotary furnace and introducing heat into the furnace barrel by generating the flame, thereby beginning a melt cycle,   introducing the inert gas streams into an inlet to the injection manifold, thereby directing the inert gas streams through the injection orifices and into the inerting region, after a predetermined condition has been met.   
     
     
         5 . The method of  claim 4 , wherein the predetermined condition is selected from the group consisting of:
 at the start of a breakdown phase,   at a predetermined time after the beginning of the melt cycle, and   at a predetermined time prior to the end of the melt cycle.   
     
     
         6 . The method of  claim 4 , wherein the predetermined time prior to the end of the melt cycle is 10 minutes. 
     
     
         7 . The method of  claim 4 , wherein the start of the breakdown phase may be identified by a factor selected from the group consisting of:
 a change in the current drawn by the rotation motor,   a change in the flue gas temperature,   a change in the total cumulative BTU energy input per pound of charge,   determined by the programmable logic controller,   operator observation.   
     
     
         8 . The method of  claim 4 , wherein:
 the rate at which the heat is introduced into the furnace barrel is determined by a burner firing rate,   the burner comprises an oxidizer ratio, and   the furnace barrel comprises a rotation rate,   
       wherein, during the breakdown phase one or more actions may be taken, the actions are selected from the group consisting of:
 the burner firing rate may be changed, 
 the burner oxidizer ratio may be changed, 
 the barrel rotation rate may be slowed, 
 the barrel rotation rate may be jogged, and 
 the barrel rotation rate may be stopped.